In the conventional workflow for digital radiological imaging, an x-ray operator or technician may routinely check the obtained images to determine whether or not the image appears to have been properly captured and to show the required portions of patient anatomy for a particular exam. Typically, a reduced-size image is reviewed on a low- to medium-resolution display monitor for this function. With many systems, the full-resolution image may alternately be available for review by the x-ray operator, a portion at a time, with additional operation steps. For example, clicking a zoom button on the capture console can invoke a pan function that allows the x-ray operator to navigate through the entire high-resolution image, section by section. However, this type of painstaking review can be quite time-consuming and is, therefore, rarely conducted in practice. Instead, the operator views the reduced-scale image, observes overall image appearance without detailed image quality assessment, and either approves the image for forwarding to the radiologist or requests a re-take. Upon approval, the full-resolution image is then stored for later assessment by a radiologist. Often, however, image quality problems overlooked by the x-ray operator or not readily visible to the operator are identified by the radiologist, hours or days afterwards.
In this conventional workflow, the initial review by the x-ray operator based on the reduced-size image is subjective and provides only a coarse estimation of the image quality and overall anatomy position. Timing and workload pressures tend to worsen the problem. It would be useful to have more information about image quality available to the operator at this stage in the radiology image processing workflow. If, for example, the operator were able to easily determine that there were an image quality problem that might compromise diagnosis, appropriate steps could be taken to re-capture the image during the same examination session. The patient and imaging personnel would not be required to schedule another examination session if problems with image quality could be detected at this initial review stage.
One problem of particular interest for Computed Radiography (CR) imaging systems relates to image speckle. Speckle is one type of image noise that occurs due to the inherent sensitivity of the CR storage phosphor plates used for x-ray image capture. The storage phosphor plates receive and accumulate incident ambient radiation during the time between imaging sessions. Such ambient or environmental radiation includes cosmic rays, X-rays emitted from nearby X-ray sources, and trace radiation sources. It can even include radiation from the CR phosphor plate itself and from its surroundings. Recommendation can be made to erase the CR phosphor plates more frequently, however some residual amount of speckle is still possible.
At the reduced-size display resolution typically used by an operator in performing the initial review of digital radiographic images, speckle is by-and-large imperceptible. In most cases, speckle can only be detected in the full-resolution digital image that is reviewed at a later time by the radiologist.
Thus, it would be useful to have utilities available for speckle detection at an earlier time in the radiographic imaging workflow.